1. Field of the Invention
The present invention relates generally to sunglasses having relatively rotatable polarized lenses over one another for rotation for varying the amount of light transmitted through the lenses.
2. Description of the Related Art
U.S. Pat. No. 2,005,426 discloses a pair of sunglasses having two superimposed polarized lenses for each eye mounted in a pair of ordinary spectacle frames. One of the two lenses is permanently mounted in the frame while the other is rotatably held by lugs in a position adjacent the first lens. The lugs hold the rotatable lenses fictionally against free movement but not so tightly that the user cannot easily rotate the lenses if desired.
U.S. Pat. No. 2,565,362 discloses a variable density goggle in which the lens mounting assembly includes a pair of light polarizing lenses that are fixed relative to the mounting assembly. Between the lenses are mounted a pair of circularly shaped light polarizing elements each having notched or toothed edges over one quarter of its periphery for engagement with a centrally positioned lens control gear which is similarly notched or toothed. The gear element is affixed to a forwardly extending shaft, onto which is applied a knurled turning knob which enables the rotatable lenses to be rotated.
Additional glasses and optical apparatus including polarizing lens elements are disclosed, for example, in U.S. Pat. No. 2,380,481, showing a worm gear across the top of the frame; U.S. Pat. No. 4,595,262 in which groups of polarized lens elements are synchronized in rotation through a centrally mounted gear; and U.S. Pat. No. 2,422,287 disclosing a centrally located turning knob which operates a control arm fixed to a link between rotatable lenses.